Laser Processing of Display Components for Electronic Devices

ABSTRACT

Electronic devices may be provided with display structures such as glass and polymer layers in a liquid crystal display. The glass layers may serve as substrates for components such as a color filter layer and thin-film transistor layer. The polymer layers may include films such as a polarizer film and other optical films. During fabrication of a display, the polymer layers and glass layers may be laminated to one another. Portions of the polymer layers may extend past the edges of the glass layers. Laser cutting techniques may be used to trim away excess portions of the polymer layer that do not overlap underlying portions of the glass layers. Laser cutting may involve application of an adjustable infrared laser beam.

This application is a continuation of U.S. patent application Ser. No.13/021,183, filed Feb. 4, 2011, which is hereby incorporated byreference herein in its entirety. This application claims the benefit ofand claims priority to U.S. patent application Ser. No. 13/021,183,filed Feb. 4, 2011.

BACKGROUND

This relates generally to manufacturing techniques for electronicdevices, and, more particularly, to use of laser processing techniquesin the construction of electronic device structures such as displaystructures

Displays are widely used in electronic devices to display images.Displays such as liquid crystal displays display images by controllingliquid crystal material associated with an array of image pixels. Atypical liquid crystal display has a color filter layer and athin-film-transistor layer between which the liquid crystal material isinterposed. Polarizer layers may be formed on the upper and lowersurfaces of the color filter layer and thin-film-transistor layer.Additional optical films may also be present.

As part of the process of forming a liquid crystal display, it isnecessary to cut sheets of polarizer film and other optical films tosize. For example, when forming a display for a handheld device such asa cellular telephone, it is necessary to form a small rectangular pieceof polarizer film for the cellular telephone display. After the desiredpiece of optical film has been cut from a larger sheet, it can belaminated to other structures to form a finished display.

Die cutting techniques are typically used to cut rectangular pieces ofpolarizer film and other optical films from larger sheets. Difficultiescan arise, however, in maintaining desired manufacturing tolerancesduring die cutting and lamination processes during display fabrication.

It would therefore be desirable to be able to provide enhancedtechniques for manufacturing displays for electronic devices.

SUMMARY

Displays for electronic devices may be formed by laminating displaylayers together. The display layers in a display may include glasslayers such as glass substrate layers associated with a color filterarray and a thin-film transistor layer or other structures. The displaylayers may also include layers of other materials. As an example, thedisplay layers may include optical films such as compensating films,diffusers, polarizers, antireflection coatings, and other layers formedfrom materials such as polymers.

In fabricating a display, layers of the display may be attached to oneanother using adhesive. With one suitable arrangement, glass layers forthe display may be cut to their final size. Slightly oversized polymerlayers may be attached to the surface of the glass layers. The polymerlayers may be sized so that portions of the polymer layers do notoverlap the glass layers, but rather overhang the edges of the glasslayers.

Laser cutting techniques may be used in trimming away these excessportions of the polymer layers. For example, an infrared laser beam maybe applied along the edge of the glass layers to remove the overhangingparts of the polymer layers. The resulting structure will have polymerlayers with edges that are in alignment with the edges of the glasslayers.

The size and shape of the laser spot that is created on the displaylayers during laser cutting operations can be adjusted. For example, thespot can be elongated when cutting along straight edges for a displayand can be formed into a more circular shape when cutting along curvedportions of a display such as around display corners.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a system of the type that may be used infabricating display structures for an electronic device using laserprocessing techniques in accordance with an embodiment of the presentinvention.

FIG. 2A is a perspective view of an illustrative electronic device suchas a handheld electronic device that may be provided with a display thathas been fabricated using laser processing techniques in accordance withan embodiment of the present invention.

FIG. 2B is a perspective view of an illustrative electronic device suchas a portable computer that may be provided with a display that has beenfabricated using laser processing techniques in accordance with anembodiment of the present invention.

FIG. 3 is a cross-sectional side view of an illustrative displaycontaining layers of material of the type that may be processed using alaser cutting system in accordance with an embodiment of the presentinvention.

FIG. 4A is a cross-sectional side view of illustrative displaystructures showing how display layers such as polymer optical films maybe trimmed using laser cutting techniques in accordance with anembodiment of the present invention.

FIG. 4B is a cross-sectional side view of the illustrative displaystructures of FIG. 4A following laser trimming to remove excess portionsof the optical films in accordance with an embodiment of the presentinvention.

FIG. 5 is a diagram of an illustrative laser processing system showinghow laser cutting equipment may produce a controlled laser beam for usein cutting layers of material during fabrication of a display for anelectronic device in accordance with an embodiment of the presentinvention.

FIG. 6 is a cross-sectional side view of display structures includinglayers such as an antireflection coating layer and a touch sensor layerthat are being trimmed to align the edges of these layers with otherdisplay layers in a display in accordance with an embodiment of thepresent invention.

FIG. 7A is a cross-sectional side view of illustrative displaystructures that include display layers such as a color filter arraylayer and a thin-film-transistor layer and an associated polymer filmsuch as a layer of polarizing material that is being cut using lasercutting equipment in accordance with an embodiment of the presentinvention.

FIG. 7B is top view of the illustrative display structures of FIG. 7Ashowing where alignment marks may be located on the display structuresin accordance with an embodiment of the present invention.

FIG. 8A is a diagram showing how a laser beam may be directed toward aworkpiece parallel to a surface normal associated with the exposedsurface of a workpiece in accordance with an embodiment of the presentinvention.

FIG. 8B is a diagram of an illustrative laser beam spot of the type thatmay be associated with the laser beam of FIG. 8A on the surface of theworkpiece in accordance with an embodiment of the present invention.

FIG. 9A is a diagram showing how a laser beam may be directed toward aworkpiece at a non-zero angle with respect to a surface normalassociated with the exposed surface of a workpiece in accordance with anembodiment of the present invention.

FIG. 9B is a diagram of an illustrative laser beam spot of the type thatmay be associated with the laser beam of FIG. 9A on the surface of theworkpiece in accordance with an embodiment of the present invention.

FIG. 10 is a graph in which laser beam intensity has been plotted as afunction of position for a laser beam with a round cross section of thetype that may be used in cutting layers of material for a display inaccordance with an embodiment of the present invention.

FIG. 11 is a graph in which laser beam intensity has been plotted as afunction of position for a laser beam with an elongated cross section ofthe type that may be used in cutting layers of material for a display inaccordance with an embodiment of the present invention.

FIG. 12 is a diagram showing how a laser cut may be made by translatinga laser beam with an elongated cross section along a direction parallelto the longitudinal axis of the beam cross section in accordance with anembodiment of the present invention.

FIG. 13A is a diagram showing how a laser beam with a circularcross-sectional profile may be used in cutting optical films into shapeswith curved edges in accordance with an embodiment of the presentinvention.

FIG. 13B is a top view of a portion of a laser-cut structure such as andisplay layer that has been cut using a laser with a circular crosssection in accordance with an embodiment of the present invention.

FIG. 14 is a diagram showing how a laser beam with a variable-shapecross-sectional profile may be used in cutting display layers intoshapes with curved edges in accordance with an embodiment of the presentinvention.

FIG. 15 is a flow chart of illustrative steps involved in using laserprocessing techniques in forming electronic device structures such asdisplay structures in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Displays are widely used in electronic devices. For example, displaysmay be used in computer monitors, laptop computers, media players,cellular telephones and other handheld devices, tablet computers,televisions, and other equipment. Displays may be based on plasmatechnology, organic light-emitting-diode technology, liquid crystalstructures, etc.

Displays generally include layers of materials. For example, a liquidcrystal display may include a color filter array layer that includescolored filter elements, a thin-film transistor layer that includesthin-film transistors for controlling the application of electric fieldsto liquid crystal image pixels. A cover layer may be used to cover thedisplay. The cover layer and other display layers such as the coloredfilter array layer and thin-film-transistor layer are typically formedfrom glass but may, if desired, by formed from other substrate materialssuch as polymers.

Numerous additional display layers are generally associated with adisplay. For example, a typical liquid crystal display may includelayers associated with polarizers, antireflection coatings, substratesfor touch sensor arrays, birefringent (compensating) films, light guideplates, diffusers, etc. These layers, which are sometimes referred to asoptical films are often formed from polymers.

In conventional display fabrication arrangements, glass layers may becut using scribe-and-break techniques. Polymer layers may conventionallybe cut using die stamping techniques. Layers that have been cut in thisway may be laminated using lamination equipment.

To enhance throughput and alignment accuracy relative to conventionaldisplay fabrication methods, laser cutting techniques may be used to cutelectronic device structures such as the layers associated with anelectronic device display. Polymers can be readily cut using lasers suchas infrared lasers, so the use of laser cutting to trim polymer layerswith respect to other display layers is sometimes described herein as anexample. If desired, other display layers such as display layers formedfrom glass, ceramic, carbon-fiber composites and other materials may bepatterned using laser processing techniques. The cutting of displaylayers formed from material such as polymers is merely an example.

A schematic diagram of an illustrative laser cutting system is shown inFIG. 1. As shown in FIG. 1, laser cutting equipment 10 may include alaser such as laser 12 and beam shaping and positioning equipment 16.Equipment 10 may shape and position laser beam 14 on workpiece 18.Workpiece 18 may include display structures such one or more layers ofmaterial in a display or other suitable electronic device structures(e.g., one or more layers of polymer, one or more layers of glass, oneor more layers of ceramic, one or more fiber-based composite layers,combinations of such layers, etc.).

Laser 12 may be, for example, a continuous wave (CW) or pulsed laserthat produces light at wavelengths from about 150 nm to about 20 microns(e.g., light at ultraviolet, visible, or infrared wavelenghts), and,more preferably a laser that produces infrared light at a wavelength inthe range of 1 to 20 microns, 1 to 12 microns, or 9 to 12 microns. Inthe infrared spectrum, high-power laser sources are widely available andmost polymers are at least somewhat opaque and able to readily absorbincoming laser light. An example of a laser type that may be used forlaser 12 is a carbon dioxide (CO₂) laser that produces light at one ormore wavelengths in the range of about 9.2 to 11.4 microns). Other typesof lasers may be used and other wavelengths of laser light may begenerated. For example, laser 12 may be a diode laser, a solid statelaser, a gas laser other than a CO2 laser, or any other suitable type oflaser.

Laser 12 may produce a pulsed or CW laser beam such as beam 14. Theshape of beam 14 and the position of beam 14 relative to workpiece 18may be controlled using beam shaping and positioning equipment 16.Equipment 16 may include optical components such as lenses, metallizedmirrors, mirrors formed from prisms, mirrors formed from dielectricstacks, diffusers, beam conditioners, filters, deformable mirrors,adjustable shutters, and other optical components. Equipment 16 may alsoinclude positioners such as motors, solenoids, and other components thatcan control the position of the optical components of beam shaping andpositioning equipment 16 relative to workpiece 18 (e.g., by rasteringthe beam across the surface of workpiece, by laterally translating thebeam and/or workpiece 18 relative to each other, by adjusting thedistance between optical components in equipment 16, be deformingdeformable optical structures, etc.).

In a typical scenario, laser 12 may produce about 10 to 100 W of outputpower or other suitable amounts such as less than 50 W of power, morethan 20 W of power, etc. Beam 14 may be focused to a spot on workpiece18 that has a spot size (e.g., a 1/e² diameter) of about 100 to 500microns in diameter. Under laser illumination conditions such as these,optical films such as polarizer layers and other polymer layers inworkpiece 18 will be cut (e.g., by thermal disassociation of the bondsin the polymer material or other decomposition mechanisms such asablation).

A perspective view of an illustrative electronic device such as ahandheld electronic device that may be provided with a displaycontaining laser-cut materials such as layers processed using laserprocessing equipment 10 of FIG. 1 is shown in FIG. 2A. As shown in FIG.2A, electronic device 20 may have a housing such as housing 22. Housing22 may be formed from materials such as plastic, glass, ceramic, metal,fiber composites, and combinations of these materials. Housing 22 mayhave one or more sections. In the arrangement of FIG. 2A, device 20 hasa front face and a rear face. Display 24, which may be formed fromdisplay structures in workpiece 18 of FIG. 1, may be mounted on thefront face of housing 22. Openings 26 may be provided in display 24. Forexample, openings 26 may be used to form speaker ports, button openings,and other openings in a cover glass layer for display 24 or in otherdisplay layers.

A perspective view of another illustrative electronic device of the typethat may be provided with a display that has been fabricated using laserprocessing equipment such as laser processing equipment 10 of FIG. 1 isshown in FIG. 2B. In the example of FIG. 2B, housing 22 has upperportion 22A and lower portion 22B. Portions 22A and 22B may be attachedusing a hinge. Upper portion 22A may be used to house display 24.Processing circuitry and input-output components such as track pad 28and keyboard 30 may be provided in lower portion 22B. Device 20 of FIG.2B may be, for example, a portable computer.

In other illustrative electronic devices (e.g., tablet computers, musicplayers, etc.), displays such as display 24 and other electronic devicecomponents may be mounted in housings 22 with other configurations. Thedisplay mounting arrangements of FIGS. 2A and 2B are merelyillustrative.

A cross-sectional side view of an illustrative display of the type thatmay be incorporated into an electronic device is shown in FIG. 3. Theillustrative display of FIG. 3 is a liquid crystal display (as anexample). Other types of displays may be provided for electronic devicesif desired.

As shown in FIG. 3, display 24 may include color filter layer 32(sometimes referred to as a color filter array layer) andthin-film-transistor layer 34. Color filter layer 32 may include anarray of colored filter elements. In a typical arrangement, the pixelsof layer 32 each include three types of colored pixels (e.g., red,green, and blue subpixels). Liquid crystal layer 36 includes liquidcrystal material and is generally interposed between color filter layer32 and thin-film-transistor layer 34. Thin-film-transistor layer 34 mayinclude electrical components such as thin film transistors, capacitors,and electrodes for controlling the electric fields that are applied toliquid crystal layer 36.

Optical film layers 38 and 40 and display layers 42 may be formed aboveand below color filter layer 12, liquid crystal layer 16, andthin-film-transistor layer 14. Optical films 18 and 20 may includestructures such as quarter-wave plates, half-wave plates, diffusingfilms, optical adhesives, and birefringent compensating layers. Displaylayers 42 may include films of this type and/or other display structuressuch as a cover glass layer or polymer cover layer, an antireflectioncoating layer, coatings for resisting fingerprints and scratching, atouch sensor array (e.g., a touch sensor array of transparent capacitiveelectrodes such as indium tin oxide electrodes patterned on a clearsubstrate such as a glass or polymer substrate), etc.

Display 24 may have upper and lower polarizer layers 44 and 46.Backlight 48 may provide backside illumination for display 24. Backlight48 may include a light source such as a strip of light-emitting diodes.Backlight 48 may also include light-guide plate 48A and back reflector48B. Back reflector 48B may be located on the lower surface of thelight-guide plate to prevent light leakage and may be formed from apolymer such as white polyester or other reflective materials.Light-guide plate 48A may be formed from a clear polymer. Light from thelight source may be injected into an edge of the light-guide plate andmay scatter upwards in direction 50 through display 24. Layers ofadhesive may be interposed between the layers of display 24 duringassembly.

The layers of material in display 24 may be formed from any suitablematerials. Typical display layers above those in backlight 48 aretransparent to allow light to propagate in direction 50. Suitabledisplay layer materials include polymers, glass, ceramic, fiber-basedcomposites, etc. In a typical arrangement, the cover layer in layer 42may be formed from a glass plate, the substrates for color filter layer32 and thin-film-transistor layer 34 may be formed from glass panels,and glass or polymer may be used for forming an optional planar touchsensor array substrate for a touch sensor in layers 42. The other layersof material in display 24 (e.g., the coating layers and other displaylayers in layers 42, upper and lower polarizers 44 and 46, optical films40 and 46, and the layers in backlight 48) are typically formed frompolymers. This is, however, merely an example. In some displays, some ofthe layers that are often formed form polymers may be formed form glass,ceramic, or other materials and some of the layers that are often formedfrom glass layers may be formed from polymer, ceramic, or othermaterials. Polymer layers tend to be cut at lower laser power densitiesthan non-polymer layers, so the use of laser processing equipment 10 ofFIG. 1 to cut through polymer layers in the structures of display 24 isgenerally described herein as an example. As described in connectionwith FIG. 1, laser processing equipment 10 may be used in processingglass display layers or other non-polymer electronic device structuresif desired.

The use of laser processing equipment 10 to cut polymers in structuressuch as display 24 is illustrated in the example of FIGS. 4A and 4B. Inthe example of FIGS. 4A and 4B and other illustrative examples describedherein, the structures that make up some or all of display 24 aresometimes referred to as forming a workpiece (i.e., workpiece 18 of FIG.1), because laser processing equipment 10 is being used to process thesestructures to form a display or other desired finished electronic devicestructures.

FIG. 4A is a cross-sectional side view of a workpiece (workpiece 18)having one or more layers 18A and one or more layers 18B. Layers 18A maybe polymer display layers such as optical films, polymer coatings,polymer touch panel substrates, polarizers, etc. Layers 18B may be glassor ceramic display layers such as a color filter array layer, athin-film-transistor layer, etc. Layers 18A may be located on the uppersurface of workpiece 18 on top of layers 18B or may be interspersedamong layers 18B.

In the scenario illustrated in FIG. 4A, layers 18A have been precut to asize that is somewhat larger than layers 18B. Layers 18B may, forexample, be cut using a scribe-and-break process that creates a desiredrectangular display footprint and layers 18A may be die cut to a sizethat is slightly larger than the nominal rectangular shape for layers18B. Other techniques for cutting layers 18A and 18B may be used, ifdesired.

Over-sizing layers 18A with respect to layers 18B creates an overhangingportion such as portion 52 that does not overlap the “footprint” oflayers 18B (i.e., a portion that does not overlap the area of layers 18Bwhen viewed along vertical dimension Z). Central portion 54 of layers18A may overlap layers 18B. Although only one overlapping edge portion52 of layers 18A is shown in FIG. 4A, there may be, for example, fouroverlapping edge portions 52, each of which is associated with arespective one of four edges 56 of a rectangular set of layers 18B(e.g., the four peripheral edges of a rectangular display).

By applying laser beam 14 to layers 18A in alignment with edge 56 oflayers 18B, non-overlapping edge portion 52 of layers 18A may be trimmedfrom main overlapping portion 54 of layers 18A. After trimming excessportions of layers 18A from workpiece 18 in this way, workpiece 18 mayappear as shown in FIG. 4B. As shown in FIG. 4B, portion 52 of layers18A is no longer present following laser trimming, so that edge 56 oflayers 18A is aligned with edge 56 of layers 18B. The accuracy of thistype of laser trimming may surpass the accuracy associated with typicaldie cutting and lamination processes. For example, using a spot size ofless than 0.05 mm and positioning techniques that are able to locatebeam 14 relative to edge 56 of layers 18B within +/−0.05 mm, thelocation of trimmed edge 56 of layers 18A may be aligned to the edge oflayers 18B within +/−0.1 mm, whereas conventional die cut processestypically exhibit size tolerances of 0.2 mm and conventional laminationprocesses typically exhibit edge location tolerances of about 0.2 mm.

FIG. 5 is a diagram of illustrative laser processing equipment 10 of thetype that may be used in cutting through display structures such aspolymer display films or in cutting other suitable electronic devicestructures. As shown in FIG. 5, equipment 10 may include a control unitsuch as control unit 58 that is interconnected with other electroniccomponents in equipment 10 using one or more communications paths 74.Control unit 58 may use a camera such as camera 60 or other sensors tomonitor the position of laser beam 14 on surface 62 of workpiece 18. Forexample, control unit 58 may use camera 60 to detect edges and alignmentmarks on workpiece 18 to facilitate accurate positioning of the laserspot on workpiece 18. Control unit 58 may be based on computingequipment such as one or more processors, memory chips, networkedcomputers, stand-alone computers, and other computing equipment. A usermay manually control the operation of components in system 10 usingbuttons, knobs, and other user input interface components that areassociated with the components of system 10 and/or by using a touchscreen, on-screen options, keyboard, buttons, mouse, or other user inputinterface components associated with control unit 58. Control unit 58may also automatically control equipment 10 (e.g., based on sensor inputsuch as input from camera 60).

Control unit 58 may issue control signals that control the operation ofone or more positioners 64. Positioners 64 may be associated with thecomponents of laser processing system 10 such as laser 12, beam shapingequipment 66, optical components 68 (e.g., mirrors, lenses, etc.), andworkpiece 18. Positioners 64 may include motors, solenoids, and othersuitable equipment for making position adjustments. Position adjustmentsmay be made in linear dimensions X, Y, and Z and in any of therotational (angular) positions about these axes.

Laser beam 14 may be shaped using optical components 66 and 68.Components 66 and 68 may include lenses, filters, mirrors, and otheroptical components for shaping and positioning beam 14 relative toworkpiece 18. For example, components 66 may include lenses and othercomponents for homogenizing or otherwise conditioning beam 14.Components 66 may be interposed within beam 14 at one or more locations.The illustrative configuration of FIG. 5 in which components 66 liebetween laser 12 and optical components 68 is merely illustrative.

Optical components 68 such as mirrors and other components may bepositioned using positioners 64. By laterally translating mirrors orother optical components, the lateral position of beam 14 may becontrolled. For example, control unit 58 may direct a positioner onwhich a mirror has been mounted from position 70 to position 72, therebytranslating reflected beam 14 so that it passes along path 14″ ratherthan path 14′. Rotational control of components 68 (e.g., mirrors) mayalso be used in adjusting the relative position of beam 14 an workpiece18. For example, by rotating a mirror or other component 68, beam 14 maybe deflected so that it passes along path 14′″ rather than path 14′.Combinations of beam rastering (e.g., positioner adjustment to deflectbeam 14 at a desired angle θ) and translation (e.g., positioneradjustment to change the lateral position of beam 14 by a desired amountΔX) may be used in controlling beam placement if desired. Control unit58 may also control the output power from laser 12 by issuing controlcommands over communications path 74 and may control the state ofdeformable mirrors and other optical components 66 and 68 (e.g., toadjust beam intensity profiles, beam shapes, etc.).

FIG. 6 shows how laser 12 may be used to trim portions of a workpiecethat includes a touch sensor layer (e.g., touch sensor layer 90, whichmay have a polymer substrate and conductive indium-tin-oxide capacitorelectrodes for forming a capacitive touch sensor array). Duringtrimming, laser beam 14 may be used to remove portion 52 of layers 18A.Layers 18A may be (for example) polymer layers including layer 92 (e.g.,an antireflection layer or other coating layer), touch sensor layer 90,and layer 94 (e.g., a polarizer layer, other optical films, etc.). Laserbeam 14 may have sufficient intensity to cut through all of layers 18Asimultaneously. In scenarios in which layers 18B are formed form adurable substrate material such as glass or ceramic, stray light frombeam 14 will not generally affect layers 18B (i.e., layers 18B will notbe cut) during the trimming process that removes excess portions oflayers 18A.

FIG. 7 a shows how laser beam 14 may be used to remove polymer layers18A (e.g., a polarizer layer and/or other optical films) from underlyingglass or ceramic layers 18B (e.g., color filter array layer 98 andthin-film transistor layer 96). Camera 60 may be used to capture imagesof layers 18A and 18B. For example, camera 60 may be used to view theposition of edge 56 of layers 18B. Control unit 58 (FIG. 5) may controlbeam shaping and positioning equipment 16 so as to position beam 14relative to workpiece 18 with beam 14 in alignment with edge 56. Controlunit 58 may determine how to adjust beam shaping and positioningequipment 16 in response to manual operator input and/or automatic imagerecognition software running an edge detection routine or other controlalgorithms on control unit 58.

To assist a user of equipment 10 and/or the automatic image recognitionsoftware running on control unit 58 in accurately determining thelocation of workpiece 18 (e.g., features such as edge 56 of workpiece18), one or more of the layers of workpiece 18 may be provided withvisual markers such as alignment marks 100 on color filter layer 98 inthe FIG. 7A example. Alignment marks 100 may assist equipment 10 inlocating edges such as edge 56 and in accurately positioning beam 14 inalignment with edges such as edge 56 during laser cutting operations.Alignment marks 100 may have any suitable shape (crosses, dots, lines,squares, etc.) and may be formed from metal or other suitable materials.FIG. 7B is a top view of color filter layer 98 of FIG. 7A showing howalignment marks 100 may be placed at the four corners of workpiece 18(as an example).

It may be desirable to adjust the shape of beam 14 during laserprocessing operations. For example, it may be desirable to elongate thecross-sectional shape of beam 14 in some situations and to ensure thatthe cross-sectional shape of beam 14 (i.e., the shape of the laser spotformed when beam 14 strikes the workpiece) is circular in othersituations. Laser spot shapes may be modified by controlling thesettings and positions of optical components in the path of beam 14and/or by controlling the orientation of workpiece 18 relative to beam14. Examples of components that may be used in shaping and positioningbeam 14 (e.g., components in optical components 66 and/or components 68of FIG. 5 or other components in the path of beam 14) include lenses,metallized mirrors, mirrors formed from prisms, mirrors formed fromdielectric stacks, diffusers, beam conditioners, filters, deformablemirrors, adjustable shutters, and other optical components.

An example of beam shaping by equipment 10 is shown in FIGS. 8A, 8B, 9A,and 9B. In this example, laser spot shape is altered by adjusting theincident angle of beam 14 on surface 62 of workpiece 18. If desired,other techniques may be used in shaping beam 14 (e.g., deforming beam 14using adaptive optics such as deformable mirrors, etc.). The example ofFIGS. 8A, 8B, 9A, and 9B is merely illustrative.

In the scenario illustrated in FIG. 8A, laser beam 14 is being directedonto surface 62 of workpiece 18 with an orientation that is parallel tosurface normal S (i.e., laser beam 14 is parallel to surface normal Sand is perpendicular to the plane of surface 62). Beam 14 (in thisexample) has a circular cross-sectional profile before striking surface62. As a result, beam 14 makes a circular spot when striking surface 62,as shown in FIG. 8B.

Using beam shaping and positioning equipment 16 of FIG. 1 (e.g., usingpositioners 64, laser 12, and optical components such as components 66and 68 of FIG. 5), control unit 58 can adjust the orientation of laserbeam 14 relative to workpiece 18 so that laser beam 14 is directed ontosurface 62 of workpiece 18 with an orientation that is not parallel tosurface normal S. In this situation, laser beam 14 is at a non-zeroangle A with respect to surface normal S and is not perpendicular to theplane of surface 62, as shown in FIG. 9A. Beam 14 (in this example) hasa circular cross-sectional profile before striking surface 62 ofworkpiece 18 in FIG. 9A, but the non-zero angle of incidence A of laserbeam 14 in the scenario of FIG. 9A causes beam 14 so spread out whenstriking surface 62. As a result, beam 14 makes an elongated spot whenstriking surface 62, as shown by the elliptical spot for beam 14 in FIG.9B.

In elongated spot shapes such as the elongated spot of FIG. 9B, thelateral dimension of the spot is larger parallel to longitudinal axis 76than along transverse axis 78. For example, the size of the spot alongaxis 78 may be about 100 to 500 microns and the size of the spot alongaxis 76 may be about 100 microns to 1000 microns, in the range of 100microns to 1 mm, in the range of 100 microns to 2 mm, in the range of100 microns to 4 mm, etc. By controlling the power of laser 12, thepower density of the elongated spot shape on surface 62 of FIG. 9B maybe decreased, maintained at the same level, or increased relative to thecircular spot shape of FIG. 8B.

If desired, beam (spot) shaping and positioning equipment 16 (FIG. 1)may be used in controlling the intensity profile of beam 14.Illustrative intensity profiles for beam 14 in two different operatingscenarios are shown in FIGS. 10 and 11. In FIGS. 10 and 11, beamintensity is plotted as a function of lateral distance X transverse tothe propagation axis of laser beam 14 (i.e., across the width of thespot).

A typical Gaussian profile of the type that may be associated with beam14 and the associated laser spot on workpiece 18 is shown in FIG. 10. Asshown by curve 80 of FIG. 10, a Gaussian intensity distribution ischaracterized by relatively gradual beam edges (i.e., intensity tapersoff somewhat gradually as a function of increasing lateral distance Xfrom the center of the beam).

Using beam shaping and positioning equipment 16, a beam profile of thetype shown in FIG. 11 may be produced for laser beam 14. As shown bycurve 84 of FIG. 11, a laser beam that has been shaped to form theprofile of FIG. 10 may have a portion such as central portion 86 thatdoes not monotonically increase in power and may also be characterizedby an intensity falloff at the edges of the laser beam that is moreabrupt that of the Gaussian beam of FIG. 10. This enhanced sharpness atthe boarder of the laser spot may help create sharper, more distinctcuts when cutting polymer display layers in workpiece 18. Thenon-Gaussian laser intensity profile of FIG. 11 is merely illustrative.Other non-Gaussian laser intensity profiles may be used for laser beam14 during laser cutting of display structures if desired.

FIG. 12 shows how a laser beam that has been used to form an elongatedlaser spot 14E on the surface of workpiece 18 may be used in forming astraight cut through workpiece 18. Elongated laser spot 14E may, as anexample, be produced by adjusting the angle of incidence of beam 14 orusing adjustable optics in beam shaping and positioning equipment 16 asdescribed in connection with FIGS. 9A and 9B. In the illustrativescenario of FIG. 12, the laser beam is being moved in direction 102,parallel to axis 104 of the straight cut being formed in the workpiece.

When forming a curved cut (e.g., when trimming excess in display layers18A that overhangs a curved corner portion of display layers 18B), itmay be desirable to use a circular laser spot of the type shown in FIG.8B. This type of arrangement is illustrated in the example of FIG. 13Ain which circular laser spot 14C is being moved along a curved path bybeam shaping and positioning equipment 16. FIG. 13B shows how this mayresult in layers 18A with a curved cut (e.g., a curved corner along edge56). The curved cut of FIG. 13B may help trim excess from layers 18A sothat layers 18A and 18B are accurately aligned along a curved edge 56 inunderlying layers 18B.

If desired, beam shaping and positioning equipment 16 may be used toadjust the shape of the laser spot produced by laser beam 14 in realtime during trimming operations. As shown, for example, in FIG. 14, insome portions of a cut such as along curved portions of edge 56, thelaser spot may be circular or nearly circular (see, e.g., circular spotshape 14C) and in other portions of the cut (e.g., along straightportions of edge 56), the laser spot may be adjusted by equipment 16 tohave an elongated shape such as elongated spot shape 14E. Real timeadjustments may also be made to the intensity profile of laser beam 14by equipment 16 (e.g., to use a gradual intensity profile such as theGaussian profile of FIG. 10 in some situations and to use a less gradualintensity profile such as the profile of FIG. 11 in other situations).Intensity profile adjustments and other beam adjustments (e.g., spotshape adjustments) may be made to accommodate differences in cuttingspeeds, differences in the material being cut, differences in edgeposition, etc.

FIG. 15 is a flow chart of illustrative steps involved in using laserprocessing equipment 10 of FIG. 1 in fabricating display structures andother electronic device structures for electronic device 20.

At step 106, layers of material for the electronic device structuressuch as glass display layers (e.g., layers 18B) and oversized polymerlayers (e.g., layers 18A) may be obtained and formed in appropriatesizes. For example, some or all of display layers 18B may be formedusing scribe-and-cut techniques or other arrangements suitable forcutting glass substrates (as an example). Layers 18A may be cut to sizeusing die cutting, laser cutting, or other cutting techniques suitablefor cutting polymer sheets (as an example).

At step 108, layers 18A and layers 18B may be attached to one anotherusing adhesive or other fastening techniques. For example, layers 18Aand 18B may be laminated to one another using interposed layers ofadhesive (e.g., pressure sensitive adhesive, optically clear adhesive,thermally cured adhesive, ultraviolet-light-cured adhesive, etc.).Lamination equipment may be used in laminating layers 18A and 18Btogether.

Following lamination, some of layers 18A will generally overhang edges56 (i.e., excess portions of layers 18A will protrude over the sides oflayers 18B and will not overlap layers 18B). During the operations ofstep 110, laser processing equipment 10 may use beam shaping andpositioning equipment 16 to remove the excess portions of layers 18A orto otherwise use laser beam 14 to shape and cut workpiece 18. Beamshaping and positioning equipment 16 may make adjustments to the lateraland angular position of beam 14 relative to workpiece 18 and adjustmentsto beam 14 that control the shape of the laser spot on the surface ofthe workpiece and other laser processing parameters (e.g., the speed ofspot movement relative to workpiece 18, the power of laser 12, etc.).Multiple beams 12 may be directed onto workpiece 18 at the same time, ifdesired (e.g., to form multi-beam spots or to process different portionsof edge 56 simultaneously to increase throughput).

Following laser processing to trim excess portions of layers 18A fromlayers 18B of workpiece 18 or to otherwise laser process workpiece 18,workpiece 18 (i.e., a trimmed display) may be installed in an electronicdevice. For example, a finished display such as display 24 of FIGS. 2Aand 2B may be installed in housing 22 of electronic device 20 usingelectronic device assembly equipment.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention. Theforegoing embodiments may be implemented individually or in anycombination.

What is claimed is:
 1. A method of trimming a layer of polarizer from adisplay substrate that has a peripheral edge, comprising: with a camera,gathering position information on the peripheral edge of the displaysubstrate; and with computer-controlled positioning equipment, moving alaser beam relative to the display substrate along the peripheral edgeto trim away an excess edge portion of the layer of polarizer.
 2. Themethod defined in claim 1 wherein the display substrate comprises aglass display substrate and wherein moving the laser beam relative tothe display substrate comprises laser cutting through the layer ofpolarizer without cutting the glass display substrate.
 3. The methoddefined in claim 2 further comprising: laminating the layer of polarizerand the glass display substrate together using adhesive before lasercutting through the layer of polarizer.
 4. The method defined in claim 1further comprising: with the computer-controlled positioning equipment,adjusting at least one laser processing parameter based on the positioninformation.
 5. The method defined in claim 4 wherein adjusting the atleast one laser processing parameter comprises adjusting a shape of thelaser beam based on the position information.
 6. The method defined inclaim 4 wherein adjusting the at least one laser processing parametercomprises adjusting a power of a laser that produces the laser beambased on the position information.
 7. The method defined in claim 4wherein adjusting the at least one laser processing parameter comprisesadjusting a speed of movement of the laser beam relative to the displaysubstrate based on the position information.
 8. A method of trimming alayer of polarizer from a display substrate, comprising: with a camera,gathering position data from the display substrate; with a control unit,issuing control signals to computer-controlled positioning equipmentbased on the position data; and with the computer-controlled positioningequipment, moving a laser beam relative to the display substrate basedon the control signals to laser cut through the layer of polarizer. 9.The method defined in claim 8 wherein the display substrate has aperipheral edge and wherein gathering the position data from the displaysubstrate comprises detecting the peripheral edge of the displaysubstrate.
 10. The method defined in claim 9 wherein moving the laserbeam relative to the display substrate comprises moving the laser beamrelative to the display substrate along the peripheral edge to trim awayan excess edge portion of the layer of polarizer.
 11. The method definedin claim 8 further comprising: with the computer-controlled positioningequipment, adjusting a shape of the laser beam based on the positiondata.
 12. The method defined in claim 8 wherein the display substratecomprises a glass display substrate, the method further comprising:laminating the layer of polarizer and the glass display substratetogether using adhesive before laser cutting through the layer ofpolarizer.
 13. Polarizer trimming equipment configured to trim a layerof polarizer from a display substrate, comprising: a camera configuredto gather position data from the display substrate; a laser configuredto produce a laser beam; and a positioner configured to move the laserbeam relative to the display substrate based on the position data totrim away excess portions of the layer of polarizer.
 14. The polarizertrimming equipment defined in claim 13 wherein the display substrate hasa peripheral edge and wherein the position data comprises a location ofthe peripheral edge relative to the laser.
 15. The polarizer trimmingequipment defined in claim 13 wherein the display substrate comprisesalignment marks and wherein the position data comprises locations of thealignment marks relative to the laser.
 16. The polarizer trimmingequipment defined in claim 13 wherein the laser comprises an infraredlaser.
 17. The polarizer trimming equipment defined in claim 13 furthercomprising beam shaping equipment configured to adjust a shape of thelaser beam based on the position data.
 18. The polarizer trimmingequipment defined in claim 13 further comprising a control unitconfigured to adjust a power of the laser based on the position data.19. The polarizer trimming equipment defined in claim 13 furthercomprising a control unit configured to adjust a speed at which thelaser beam is moved relative to the display substrate based on theposition data.
 20. The polarizer trimming equipment defined in claim 13wherein the display substrate comprises a glass display substrate andwherein the laser beam is configured to cut through the layer ofpolarizer without cutting the glass display layer.